The present invention relates to a pneumatic actuator which requires no movable parts to activate a relay valve to provide a timed signal to activate other pneumatic devices.
Heretofore, certain timer devices have been provided in pmeumatic contril circuits which have included mechanically adjustable signal control mechanisms to provide a signal to be applied and maintained on a valve or port in a single stroke operation of an associated device. Devices within the scope of the present invention are particularly useful as pilot valves in the operation of pneumatic systems, for example, in the food industry to provide a selectively time fluid pulse to control the operation of an associated valve controlling flow of food or liquids to containers as the containers pass along a conveyor system where accuracy of timing and reliability are important.
Such prior timing arrangements have certain disadvantages in that the adjustable timer arrangement necessarily includes movable timing parts which have to be meticulously set and maintained to provide a constant single stroke function of a pre-selected timing interval.
In addition, such prior arrangements are expensive to fabricate because of the delicate nature of the movable timing parts to insure a constant time single stroke function.